In electronic devices such as liquid crystal displays, mobile information devices such as cellular phones and tablets, digital cameras, organic EL displays, organic EL lightings, and sensors, there is a demand for a further improvement in performance in addition to size reduction and thickness reduction. As a method for producing these electronic devices less expensively, printed electronic devices in which wiring is directly printed have been attracting attention. In the production of electronic components by a printing method, since a multi-step process including exposure and development and a vacuum process such as vapor deposition can be omitted, considerable simplification of the production process is expected.
Printing methods such as ink-jet printing, screen printing, gravure printing and gravure offset printing can form a wiring with a desired pattern directly on a substrate and are thus used as simple and low-cost processes. However, the formation of a wiring with a desired pattern involves a flow of materials used for the wiring formation and this causes wet-spreading and bleeding of the materials; therefore, printing methods have a limitation in terms of forming a fine pattern with excellent linearity.
Further, the technology of forming a metal wiring by patterning a wiring-forming material through printing and subjecting the resulting wiring to thermal calcination or photocalcination has been actively studied (see, for example, Patent Document 1); however, in addition to the problem of wet-spreading and bleeding of the material at the time of printing, there is a problem in the adhesion between the resulting wiring and a substrate.
Thus, in order to solve the above-described problems so as to enable high-definition printing and thereby achieve high-definition wiring formation, the technology of arranging a layer (base layer) that serves as a wiring base has been studied. A base treatment of arranging a base layer is often performed for the purposes of inhibiting wet-spreading, bleeding and the like of a wiring-forming material applied on a substrate and thereby improving the printability.
As methods for such a base treatment, for example, a method of grafting epoxy groups to a substrate (see, for example, Patent Documents 2 and 3), a method of applying a photocatalyst on a substrate (see, for example, Patent Documents 4 and 5) and a method of applying an acrylic copolymer on a substrate (see, for example, Patent Documents 6 and 7) are known.